Doing lith prints was an eye-opening experience for me. With a glassless holder one print would be sharp as a pin and another would be a blurfest. And that was 120 film on 8x10 paper! For some quick and dirty prints maybe glassless is ok, but if you want to avoid frustration and wasted paper, a glass carrier is a must. The only problem with glass is that the prints get so sharp that you can start seeing the film grain and small dust on your prints which before were blurred away by the popping negative.